[英]TermDocumentMatrix errors in R
I have been working through numerous online examples of the {tm} package in R, attempting to create a TermDocumentMatrix. 我一直在研究R中{tm}包的许多在线示例,试图创建一个TermDocumentMatrix。 Creating and cleaning a corpus has been pretty straightforward, but I consistently encounter an error when I attempt to create a matrix.
创建和清理语料库非常简单,但是当我尝试创建矩阵时,我一直遇到错误。 The error is:
错误是:
Error in UseMethod("meta", x) : no applicable method for 'meta' applied to an object of class "character" In addition: Warning message: In mclapply(unname(content(x)), termFreq, control) : all scheduled cores encountered errors in user code
UseMethod(“meta”,x)中的错误:“meta”没有适用于类“character”对象的适用方法此外:警告消息:在mclapply(unname(content(x)),termFreq,control):all计划的核心在用户代码中遇到错误
For example, here is code from Jon Starkweather's text mining example . 例如,这里是Jon Starkweather的文本挖掘示例中的代码。 Apologies in advance for such long code, but this does produce a reproducible example.
为这么长的代码提前道歉,但这确实产生了一个可重复的例子。 Please note that the error comes at the end with the {tdm} function.
请注意,错误在{tdm}函数结束时出现。
#Read in data
policy.HTML.page <- readLines("http://policy.unt.edu/policy/3-5")
#Obtain text and remove mark-up
policy.HTML.page[186:202]
id.1 <- 3 + which(policy.HTML.page == " TOTAL UNIVERSITY </div>")
id.2 <- id.1 + 5
text.data <- policy.HTML.page[id.1:id.2]
td.1 <- gsub(pattern = "<p>", replacement = "", x = text.data,
ignore.case = TRUE, perl = FALSE, fixed = FALSE, useBytes = FALSE)
td.2 <- gsub(pattern = "</p>", replacement = "", x = td.1, ignore.case = TRUE,
perl = FALSE, fixed = FALSE, useBytes = FALSE)
text.d <- td.2; rm(text.data, td.1, td.2)
#Create corpus and clean
library(tm)
library(SnowballC)
txt <- VectorSource(text.d); rm(text.d)
txt.corpus <- Corpus(txt)
txt.corpus <- tm_map(txt.corpus, tolower)
txt.corpus <- tm_map(txt.corpus, removeNumbers)
txt.corpus <- tm_map(txt.corpus, removePunctuation)
txt.corpus <- tm_map(txt.corpus, removeWords, stopwords("english"))
txt.corpus <- tm_map(txt.corpus, stripWhitespace); #inspect(docs[1])
txt.corpus <- tm_map(txt.corpus, stemDocument)
# NOTE ERROR WHEN CREATING TDM
tdm <- TermDocumentMatrix(txt.corpus)
The link provided by jazzurro points to the solution. jazzurro提供的链接指向解决方案。 The following line of code
以下代码行
txt.corpus <- tm_map(txt.corpus, tolower)
must be changed to 必须改为
txt.corpus <- tm_map(txt.corpus, content_transformer(tolower))
There are 2 reasons for this issue in tm v0.6. 在tm v0.6中有两个原因导致此问题。
tolower
etc., tm_map
returns character vector instead of PlainTextDocument
. tolower
等术语级别转换,则tm_map
将返回字符向量而不是PlainTextDocument
。 tolower
through content_transformer
or call tm_map(corpus, PlainTextDocument)
immediately after tolower
content_transformer
调用tolower
或在tolower
之后立即调用tm_map(corpus, PlainTextDocument)
install.packages('SnowballC')
install.packages('SnowballC')
There is No need to apply content_transformer. 无需应用content_transformer。
Create the corpus in this way: 以这种方式创建语料库:
trainData_corpus <- Corpus((VectorSource(trainData$Comments)))
Try it. 试试吧。
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